There is no admission that the background art disclosed in this section legally constitutes prior art.
The use of fluid substances such, for example, as hydrogels or liquids as a soil amendment or other is well established. There are a number of different types of fluid substances including liquids and gels have been injected into the soil to help plant growth. For example, polyacrylamide (PAM), starch and polyacrylate gels have been used for this purpose. Use of hydrogels allows the retention of moisture in the soil or around crop roots. Substantial reduction in the use of irrigation water may be achieved by applying appropriate dosages of PAM to soil or other growing mediums for many applications. Reduction in the amount of irrigation water applied in agricultural and landscape applications may have the additional benefit of slowing the build-up of unwanted salts introduced through irrigation water. Additionally, additives may be incorporated into hydrogels, thereby effecting large savings in the amount of additives used, and consequently, in the amount of additives released to the environment. Such additives may include fertilizers and pesticides as well as others.
For record purposes, the following is a list of prior patents and applications disclosing various methods and devices for applying products to the soil: U.S. Pat. Nos. 1,871,529; 2,214,083; 2,789,522; 3,017,200; 3,148,643; 3,602,166; 3,791,322; 3,926,131; 4,018,170; 4,034,686; 4,178,860; 4,850,291; 5,115,750 and 5,667,019; and U.S. patent applications Nos. 2002/0148396 and 2006/0230997.
A variety of machines have been developed to facilitate the placement of hydrogels below the soil surface. These include tractor powered units that open up the soil surface through the use of specially designed plows and then drop dry granular material into the open slit. Other hand-held machines may use water and/or air to assist with insertion and transport of hydrogel solutions into soil at various depths through an injection device such as a hollow needle or spike. Landscape applications may require application of hydrogels in areas that have existing landscaping such as turf, shrubs and trees. Therefore, a machine used for many such applications should be maneuverable and compact.
A number of methods for applying hydrogels are known in the art. These include broadcasting, mixing with soil, or filling holes in the soil with a mixture of gel and a soil mix. These methods are all discussed in product literature from various manufacturers and/or distributors of these materials. Most methods are labor intensive, often involve an additional step in the planting process, and may cause damage to existing crops, plants, or turf. Each of these factors may contribute to inefficient use of the gel. Furthermore, each of these factors suffer from the disadvantage that they fail to distribute a uniform and consistent layer of the somewhat viscous gel below the surface of the soil to hold water for the plant roots. In short, the prior known distribution techniques have failed to effectively and efficiently deposit desired quantities of fluid substance below the surface of soil in a uniformly consistent manner to help plant growth or otherwise serve as an effective soil amendment.